My earlier U.S. Pat. Nos. 4,948,360 and 5,006,060, the priority of which is claimed and the content of which is incorporated herein by reference describes and claims a gas resonance device comprising a resonance tube which expands in cross section along its length from one end to the other, a heat source located at the one end of the resonance tube, and means to trigger oscillations in a gas in the resonance tube. The resonance tube is preferably of ogival form and the heat source and means to trigger oscillations in a gas in the resonance tube are preferably formed by a pulsed combustor having a pulse repetition frequency corresponding to a resonant frequency of the gas resonance tube. The pressure waves generated by such a thermally driven gas resonance device are described as operating a pressure swing gas separator or a heat pump.
My earlier patents explain that one of the main limiting factors on the efficiency of this type of gas resonance device is the wall friction that occurs between the oscillating gas in the resonance tube and the side wall cf the resonance tube. By making the side wall of the resonance tube of ogival form it is possible to reduce these wall friction losses and so improve the overall efficiency of the gas resonance device.